Reland of [ignition/turbo] Perform liveness analysis on the bytecodes

src/interpreter/control-flow-builders.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/control-flow-builders.h"
 
 namespace v8 {
 namespace internal {
 namespace interpreter {
 
@@ skipping 37 matching lines @@
   DCHECK(header_labels_.empty() || header_labels_.is_bound());
 }
 
 void LoopBuilder::LoopHeader(ZoneVector<BytecodeLabel>* additional_labels) {
   // Jumps from before the loop header into the loop violate ordering
   // requirements of bytecode basic blocks. The only entry into a loop
   // must be the loop header. Surely breaks is okay? Not if nested
   // and misplaced between the headers.
   DCHECK(break_labels_.empty() && continue_labels_.empty());
   builder()->Bind(&loop_header_);
-  for (auto& label : *additional_labels) {
-    builder()->Bind(&label);
+  if (additional_labels != nullptr) {
+    for (auto& label : *additional_labels) {
+      builder()->Bind(&label);
+    }
   }
 }
 
 void LoopBuilder::JumpToHeader(int loop_depth) {
   // Pass the proper loop nesting level to the backwards branch, to trigger
   // on-stack replacement when armed for the given loop nesting depth.
   int level = Min(loop_depth, AbstractCode::kMaxLoopNestingMarker - 1);
   // Loop must have closed form, i.e. all loop elements are within the loop,
   // the loop header precedes the body and next elements in the loop.
   DCHECK(loop_header_.is_bound());
@@ skipping 60 matching lines @@
 
 void TryFinallyBuilder::BeginFinally() { finalization_sites_.Bind(builder()); }
 
 void TryFinallyBuilder::EndFinally() {
   // Nothing to be done here.
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8